In this kind of an LED illumination system, it is required that each of the LED illumination devices emits light at a brightness according to a light adjustment. It is necessary to configure that, for example, not only the same brightness can be obtained by any LED illumination device in the case where a dimming degree in a power supply device side is 100% but also half of the same brightness can be obtained by any LED illumination device in the case where the dimming degree is 50%.
Meanwhile, since forward current/relative luminosity characteristics are uneven for every LED, even though the current of the same value is supplied from the power supply device, the brightness may be different in each of the LED illumination devices in some cases.
Therefore, conventionally, it has been adapted that the brightness of the respective LED illumination devices is measured prior to shipment to thereby have the respective LED illumination devices provided with brightness characteristic information related to the brightness thereof.
Thus, in the power supply device, by communicating with each of the LED illumination devices, the brightness characteristic information of each of the LED illumination devices is acquired, and the supply current is varied for every LED illumination device so that the respective LED illumination devices emit light with the same brightness at the respective dimming degrees (see Patent Literature 1, Patent Literature 2).